package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import io.netty.util.internal.StringUtil;
import jdk.nashorn.internal.ir.CallNode;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.StringUtils;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //解决缓存穿透
        //Shop shop= cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id, Shop.class, this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        //缓存穿透
        //Shop shop = queryWithPassThrough(id);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cacheClient
                .queryWithLogicalExpire(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        if(shop ==null){
            return Result.fail("店铺不存在!");
        }
        //7.返回
        return Result.ok(shop);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    
    /*public Shop queryWithLogicalExpire(Long id){
        String key=CACHE_SHOP_KEY+id;
        //1.从redis查询店铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断是否存在
        if(StrUtil.isBlank(shopJson)){
            //3.存在，直接返回
            return null;
        }
        //4.命中，需要先把json反序列化对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop=JSONUtil.toBean((JSONObject)redisData.getData(),Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1.未过期，直接返回店铺信息
            return shop;
        }
        //5.2.已过期，需要缓存重建
        //6.缓存重建
        //6.1.获取互斥锁
        String lockKey=LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //6.2.判断是否获取锁成功
        if(isLock){
            //6.3.成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                //重建缓存
                try {
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unlock(lockKey);
                }
            } );
        }

        //6.4.返回过期店铺信息

        return shop;
    }
*/
    public Shop queryWithMutex(Long id){
        String key=CACHE_SHOP_KEY+id;
        String lockKey= null;
        Shop shop = null;
        try {
            //1.从redis查询店铺缓存
            String shopJson = stringRedisTemplate.opsForValue().get(key);

            //2.判断是否存在
            if(StrUtil.isNotBlank(shopJson)){
                //3.存在，直接返回
                return JSONUtil.toBean(shopJson, Shop.class);
            }

            //判断命中的是否是空值
            if(shopJson !=null){
                //返回一个错误消息
                return null;
            }

            //4.实现缓存重建
            //4.1.获取互斥锁
            lockKey = "lock:shop:"+id;
            boolean isLock = tryLock(lockKey);
            //4.2.判断是否获取成功
            if(!isLock){
                //4.3.失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            //4.4.成功，根据id查询数据库
            shop = getById(id);
            //5.不存在,返回错误
            if(shop == null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }

            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //7.释放互斥锁
            unlock(lockKey);
        }

        //8.返回
        return shop;
    }
/*
    public Shop queryWithPassThrough(Long id){
        String key=CACHE_SHOP_KEY+id;
        //1.从redis查询店铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }

        //判断命中的是否是空值
        if(shopJson !=null){
            //返回一个错误消息
            return null;
        }

        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在,返回错误
        if(shop == null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }

        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //7.返回
        return shop;
    }
*/
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }
/*
    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));

    }
*/
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id ==null){
            return Result.fail("店铺不能为空");
        }
        //1.更新数据库
        updateById(shop);

        //2.删除数据库
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();

    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判读是否需要根据坐标查询
        if(x ==null || y==null){
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query().eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            //返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from =  (current -1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis，按照距离排序，分页。结果:shopId,distance
        String key=SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)

                );
        // 4.解析出id
        if(results ==null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if(list.size() <=from){
            // 没有下一页了,结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(result ->{
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }

}
